Molybdenum compounds and lubricating compositions containing them



United States Patent 3,184,410 MOLYBDENUM COMPOUNDS AND LUBRICAT- ING COMPOSITIONS CONTAINING THEM Leslie Bretherick, Windsor, England, assiguor to The British Petroleum Company Limited, London, England, a corporation of England No Drawing. Filed Aug. 5, 1964, Ser. No. 387,786 Claims priority, application Great Britain, Aug. 20, 1963, 32 ,87 1/ 63 7 Claims. (Cl. 25242.7)

This invention relates to novel molybdenum compounds having utility as lubricants and as additives therefor, and to lubricating compositions containing such compounds.

Although molybdenum disulphide (MoS behaves as a good solid lubricant (i.e., in the absence of liquid lubricant), lubricating oils containing finely divide molybdenum disulphide in suspension show little advantage under normal conditions over the base oils. This may be due to the fact that molybdenum disulphide is insoluble in mineral oils or esters.

Oil-soluble compounds containing both molybdenum and sulphur have ben proposed as additives to improve the load carrying properties of lubricants. Examples of such oil-soluble compounds are certain molybdenum a1- kyl xanthates and molybdenum dialkyldithiophosphates. Such compounds appear to decompose at the high temperatures and pressures encountered under frictional stress with the deposition of compounds containing molybdenum, sulphur and, usually, oxygen, e.g., M005 and M00 8. The solid lubricating properties of these latter compounds are not as good as those of molybdenum disulphide.

I have now discovered certain novel molybdenum com pounds which are soluble in mineral and synthetic lubricating oils and which improve the load carrying or antiwear properties of such oils.

The invention therefore, according to one aspect, consists in novel compounds of the general formula i! 0 S S (Formula I) where R and R which may be the same or different, are alkyl, alkenyl, or alkynyl groups preferably having l-20 carbon atoms, and the Xs are oxygen or sulphur atoms, at least one of the Xs being an oxygen atoms. Where R and/ or R are alkenyl or alkynyl groups, the group(s) may contain more than one multiple bond. Preferably however, R and R are alkyl groups, especially branched chain alkyl groups. It is to be understood of course that the invention includes products consisting of a mixture of different compounds in accordance with Formula I.

The invention also includes a method of preparing compounds of Formula I in which a compounds of the formula (Formula II) 3,184,410 Patented May 18, 1965 ice where the Xs are oxygen or sulphur atoms, at least one of the Xs in each ring being an oxygen atom, and R and R have the values stated previously, is reacted with sulphur, in an inert atmosphere and preferably in a solvent, e.g., the diketone shown chelated in Formula I, and at elevated temperature, e.g., l00200 C. Compounds of Formula II are known and commercially available. The diketone produced as a by-product of the reaction may be recovered for re-use, c.g., by distillation.

The invention further includes a method of preparing compounds of Formula I in which molybdenum hexacarbonyl is reacted with sulphur and a diketone or monothio diketone of the Formula R C(XCH C(X)R where X, R and R have the values stated previously for Formula I. This method of preparation has the advantage over the previous method that it avoids using the airsensitive compounds of Formula II and the reaction mixture generates its own inert atmosphere of carbon monoxide.

According to a further aspect of the invention there is provided a lubricating composition consisting essentially of a blend of a lubricating oil, which may be mineral or synthetic, and a molybdenum compound of Formula I. For most applications, e.g., for use as an engine or gear lubricant, only a small proportion, e.g., O.l5% by weight of the composition, of the molybdenum compound will be needed in the blend to confer improved load carrying or anti-wear properties on the lubricating oil. The amount of molybdenum compound that can be dissolved in the lubricating oil will depend primarily on the nature of the alkyl groups R and it is to be understood that the composition may contain suspended as well as dissolved molybdenum compound of Formula I. In the use of such a lubricating composition, the dissolved molybdenum compound will gradually be converted to molybdenum disulphide and other compounds and at the same time a corresponding amount of the undissolved material will go into solution.

Actual preparations of a number of compounds in accordance with the invention will now be described by way of example only.

EXAMPLE 1 Sample quantities of dithiomolybdenyl acetylacetonate were prepared by each of the two general methods of the invention. Actual preparative details are given as Method 1 and Method 2 below.

Method 1 A mixture of molybdenum tri-acetylacetonatc (3.93 g.) prepared by the method of Larson and Moore (J. Inorg. Chem. 1, 856, 1952), acetylacetone (25 ml.) and sublimed sulphur (0.64 g.) was stirred and refluxed in an inert atmosphere for 5 hours. The black mixture was freed of solvent by vacuum distillation and the residue dispersed in benzene. The black solid was filtered olf, Washed with benzene and dried in vacuo.

The yield was 1.7 gm.

The product so recovered is hereinafter referred to as M1.

The reaction of Method lmay be represented thus:

7 Method 2 .A mixture .of molydenum' hexacarbonyl (5 g.), sublirned sulphur (1.22 g.) and acetylacetone (2 5'rnl., i.e.,-

about 200% excess as a reaction solvent) was gently stirred and boiled under refluxfor '6 hours, when the evolution of gas had ceased. The black solid product was collected by filtratiornwashed with a little benzene j and dried in vacuo. The yield was 5.4 g.

The product'so recovered had the following analysis: 1

Product M1 was blended into an SAE 90 refined mineral lubricating oil at 1% wt. concentration and'the load carrying and anti-wear properties of the composition and of the base oil without M1 were assessed by theiwell-f known 4-ball'test, the results being tabulated bel0w.'

TABLE-1 SAE 90 Base'oil plus Measurements base oil 1% wtrMl V Mean Hertz load (kg.) 23, 31 .3 2% seconds delay load (kg.) 80 Welding load (kg.) 140 200 V EXAMPLE 2 V I A sample quantity of dithiomolybdenyl stearoylacetonate was prepared by the hexacarbonyl/diketonemethod in accordance with the invention,'as described below.

A mixture of molybdenum hexacarbonyl (2.64 g.) andstearoylacetone (20 g.) was heated at 160170 C. for

48 hours until evolutionof carbon.monoxide had slowed appreciably. Sulphur (O.64.g.) was added and, the mixture was heated at 15 0 -160 C. for a further 16 hours.

Excess diketone was removed by vacuunrdistillation, leav-' ing a'black solid residue of dithiomolybdenyl stearoylacetonate (additive M Y 7 Sufficient of the product wasdisPersedin benzene and added to aSAE.90 refined mineral oil (as used in Example 1) to give, after removal of benzeneby warming under vacuum,'a 1 percent by weight blend. The loadcarrying and anti-wear properties of the blend were assessed by the 4-ball test, and the results are. given Table 2 below.

EXAMPLES v d A sample quantity of dithiomolybdeiiyl lauroyl-pivaloylmethanate wasprepared by the hexacarbonyl/diketone method in accordancewith-ihe .invention, as described below. I

4 ing and anti-wear properties of the blend were assessed by the4-ball test, and the results are given in Table 2 below.

Additive M: Additive Ma Measurements on 1% wt.

blends in SAE 90 oil Rr=Methyl Rr=t-Butyl r BFIi-HeptadecyI R =n-Undeeyl Mean Hertz load (kg) zsfs 30. o 2% second delay load (kg.) .76 100-110 Welding load (kg.) 200 a 200 Initial seizure load (kg.) 7 I The molybdenu m compounds of the present invention ,when'used as additives for lubricating oilsare'compatible iwith other, conventional, lubricating oil additives,,e.g., antioxidants, VJ. improvers, and detergents.

'Iclaimz. I r V 1.v A compound of formula;

wherein R and R are aliphatic. hydrocarbon radicals having 1-20 carbon atoms, andthe Xs are atoms selected from. the group consisting of oxygen and sulphur, at least one of the Xs being an oxygen atom. v '2. A compoundaaccording to claim, 1: wherein R and R are'alkylgroups.

3. A method of preparing compounds of the formula wherein Ri and R are aliphatic hydrocarbon radicals having 1"20'carbon atoms, and the Xs' are atoms'selected from the group consisting of oxygen and sulphur, at least one of the Xs'bein'g anoxygen atom, which comprises reacting a compound of formula wherein R and R have the values assigned above, and ltheXs are atoms selected from the group consisting of ,oxygen and sulphur, at leastone of the Xs in each ring being an oxygen'atom, with sulphur in an inert'atmos- 'phere, andin the presence of a' solvent, at an elevated temperature.

A mixture of rnolybdenum hexacarb'onyl' (2.64 g.) and I lauroyl-pivaloyl-methane"(17.4 g., 20 ml.) was heated at 160-170 C. for 48' hours, Sulphur (0.64'g.) was added, and the mixture heated at. 150 -1607 C. "for a further 16 hours. Excessdiketone wasremoved by vacuum distillation leaving a black semi-solid residue of dithiomolybdenyl. lauroyl-pivaloyl -'methanate (additive M3). V

Suflicient of the product was dispersed benzene and added to a SAE defined mineral oil (as used in'Example .1) to give, after removal of benzene by warmingun-i der vacuum, a 1 percent by weight blend. The load-carry- ;j 4. A method according to claim '3 wherein the reaction is carried out a't a temperature'within the range C.200C.

-5. A method of preparing compounds of the formula I s S V wherein R and R are aliphatic hydrocarbon radicals having 1-20 carbon atoms, and the 'Xs are atoms selected 7 75 from the group consisting of oxygen and sulphur, at

least one of the Xs being an oxygen atom, which comprises reacting a compound of formula R C(X)CH C(X)R wherein the Xs, and R and R have the values assigned above, with sulphur and molybdenum hexacarbonyl.

6. A lubricating composition consisting essentially of a blend of a lubricating oil and a compound according to claim 1, the said compound being added in an amount sufiicient to improve the lubricating properties of the composition.

7. A lubricating composition according to claim 6 wherein the said compound is added to the extent of 0.1% to 5% by weight of the composition.

5 References Cited by the Examiner UNITED STATES PATENTS 2,951,040 8/60 Hugel et a1 260-429 X 10 DANIEL E. WYMAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NOT 3 ,184 ,410 May 18 1' Leslie Bretherick It is hereby certified that error appears in the above numbered patent reqiiring carrection and that the said Letters Patent should read as cnrrectedbelow.

Column 1, line 17, for "divide" read divided column 2 line 13 for "R C[XCH C (X) R read R C(X)CI--I C[X)l line 53, for "1952" read 1962 Signed and sealed this 19th day of October 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J BRENNER Altcsting Officer Commissioner of Patents 

1. A COMPOUND OF FORMULA
 6. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A BLEND OF A LUBRICATING OIL AND A COMPOUND ACCORDING TO CLAIM 1, THE SAID COMPONENT BEING ADDED IN AN AMOUND SUFFICIENT TO IMPROVE THE LUBRICATING PROPERTIES OF THE COMPOSITON. 